Process of making phosphorus nitride



May 28, 1929. c. G. MlNr-:R

PROCESS OF MAKING PHOSPHORUS NITRIDE FilediNov. 6. 1922 25 ing' these elements 55 phosphorus Patented May 28, 1929.

CLAUDE G. MINER, OF BERKELEY, CALIFORNIA.

PROCESS OF MAKING PHOSPHORUS NITRIDE.

Application. filed November 6, 1922. Serial No. 599,459.

T his invention relates to a method of treating phosphorus bearing ggfs to obtain phosphorous and then causin,c he phospliorus to unite with nitrogen from the air, thus g1v- 5 ing phosphorus nitride which can, if desired, be treated with steam at an elevated temperature to give ammonium phosphate.

Phosphorus is an expensive element of soil fertility and one that is deficient in largev .10 areas of soil. At present, Where raw phos-l phaterock is treated ulth sulphuric, acid to give the more soluble acid phosphate rock, the actual phosphorusgconteut of the product is only about percent. The rest is essentially 15 Waste material upon which freight, handling charges, etc., must be paid.

About the same conditions exist withv regard to nitrogen fertilizers. The standard nitrogen fertilizers containabout 16 to 21 percent 20 of nitrogen, the rest beingessentially waste material which involves additional transportation and handling charges.

This invention gives a process whereby a more highly concentrated fertilizer contain- (nitrogen and phosphorus) can be manufactured, and the transportation and handling charges thereby greatly reduced.

In the manufacture of the fertilizer itself, the present process has many advantages over other existent processes for the fixation of nitrogen. From start to finished product, either phosphorus nitride or ammonium phosphate, the process is continuous. This feature makes possible a great saving in labor t costs. Standard working conditions` are also a feature of this process; for instance, the

process does not employ excessive'presfsures or temperatures. The machinery is'essen- 40 tially standard, now being utilized for other purposes. A

' The present invention therefore contemplates therformation of a phosphorus nitride,

- which is a condensed fertilizer, being gradually decomposed-in the soil into forms that can be `assimilated by plant life.

to obtain a form immediately soluble, then the nitride is treated with steam at an elevated temperature to give ammonium phosphate.

The first step of the process is the treatment of phosphate rock by any standard method for the production of phosphorus. The resulting vapors of phosphorusand oxides of carbon are passedv into a condenser where the preferably is condensed to a liquid state.l The liquid phosphorus is passed If it is desired w f1 into a reaction chamber, into which nitrogen, as pure as possible, is admitted. To facilitate thereaction between the nitrogen and phosphorus an energetic electrical discharge or a catalyst is used in the reaction chamber, Where nitride of phosphorus is formed. A high tension arc of low amperage ora static electrical discharge is suitable.` The reaction chamber preferably is maintained at a temperature above the boiling point of phosphorusbut below a red heat. In the presence of an energetic electrical discharge the reaction is active and rapid. A large induction coil used in laboratory tests also gave very good results. Catalytic agentsalso cause the reaction to `take place, but I prefer an energetic electrical discharge. Iron, nickel, platinized asbestos, finely divided magnesium, etc.. make good catalysts for the reaction. T he phosphorus nitride is a grayish amorphous material which is non-hygroscopic and stable at 4ordinary temperatures. At high temperatures, however, it is a pdwerful reducing agent and burns in the air, henceA the nitride must be cooled in an inert atmosphere such as nitrogen gas. If 1t is deslred to make ammonium phosphate, the lnitride is" allowed to pass into another chamber or into another part of the same chamber, 'where the temperature is maintained at from 180o-200 C. -In .to this chamber is passed steam which with the phosphorus nitride at ,180o-200i@ gives ammonium phosphate of a non-hygroscopic character.

The accompanyi g drawings illustrate diagrammatically one arrangement of apparatus suitable for the carrying outof the process of my invention.

On the drawings,

. Fig. 1 is a vertical sectional view of the complete plant, and t Fig. 2 is a cross-sectionalview action chamber 10 of Fig. 1.

The process is carried out in the apparatus illustrated as follows: p

.Phosphate rock and sand are fed from the hopper 1 into the rotary calciner 2, Where the of the remixture is preheated by means of waste gases from the condenser 'a'. From the rotary caleiner 2 the hot mixture of sand and phosphate rock passes into the'electric furnace 4 by `Way of the hopper 3 and the screw con- -veyor 18. Coke in proper proportion is mixed with the sand and phosphate rock as it passes from the calciner 2 to the furnace 4. The phosphorus vapor and carbon monoxide condenser.

i into the vreaction chamber 10.l The reaction 'chamber 10 can be made-of iron lined with brick.i Electrodes e, f and g'project from! the inner walls of the reaction chamber 10.

Vit'hin the reaction chamber 10 is a rotary' shaft 17 carrying the4 radial electrodes, a, 'b

7nitride Whicli) consists in bringing together and c. As the shaft 17 rotates in a direction opposite to the direction of rotation ofthe chamber 10, electrodes l1, band c pass close to electrodes e, vand g,' giving high tension arcs of low amperage which cause a rapid it-ed'to the above disclosure except as may:

reaction betweenfthe phosphorus and nitrogen, duit .16J forming nitride. of phosphorus. The nitride passes into a chamber 11 where it cools in an atmosphere of nitrogen. If it is desired to make ammonium phosphate, the nitride is conveyed by a screw device 12 into another chamber 13 where it -is brought into contact with steam at a temperature of about 180-200o C. introduced through the pipe 14.

C This gives ammonium phosphate Thus the i', process produces a complete continuous procedure for the manufacture of either phosphorus nitride or ammonium phosphate with a moderate consumption of power and low labor costs. I

The process takes about two volumes of nitrogen to one volume of phosphorus vapor.

If ammonium .phosphate is formed in the conduit 8 just enough steam is admitted to form an anhydrous ammonium phosphate.

The ratios in which the phosphate rock, sand l and. coke are mixed are in accordance with standard practice. for the manufacture of phosphorus. A i

It is naturally possible for one skilled in the art to vary the details of-theabove procedure as well as the proportions of the v.different ingredients,4 kind of catalyst, etc., without departing from thespirit of the invention. Therefore I do not wish to be limbe required by the claims.v y l l Having thus described my invention. what.

I claim and desire to securelby Letters Patent is 1. The process of producing phosphorusnitride which consists inl bringing phosbut below a red heat.

The phosphorus collectedthe latter being supplied through coli-- phoru's and nitrogen together in proper proportion in a reaction chamber at a temperature above the boiling point of phosphprus 2. The process of producing phosphorus nitridel which cvon'sists in bringing phosphorus and nitrogen together in proper proportion in a reactionv chamber atan elevated temperature, and then cooling'said nitride in an inert atmosphere. e

3. The .process of producing phosphorus nitride which consists in bringing together phosphorus and nitrogen in proper proportion in a reaction chamber in the presence of an energetic electric discharge.

4. The process of producing phosphorus boiling point of phosphorus but below a. red' heat.

6. The process of producing phosphorus nitride which consists in bringing together phosphorus and nitrogen in proper vproportion in a reaction chamber in thepresence of a high tension arc at an elevated-temperature.

7. The process of producing phosphorus nitride which consists in bringing together phosphorus and nitrogen in proper proportion in a reaction chamber in the presence of v a high tension arc above the boiling point of p phosphorus but below a red heat.

' 8. The process of producing phosphorus nitride which consists in bringing together phosphorus and nitrogen in proper proportion in a reactionchamber in the presence of an -energeticelectrical discharge aty an ele' i vated temperature, and then cooling the nitride in an inert atmosphere.

' 9. The process of producing phosphorus Vnitride 'which consists in bringing 'together phosphorus and nitrogen in proper propor-I tion 1n a reaction chamber 1n the presence of ian -energetic electrical discharge 4at an elevated temperature, and thencooling the nitride in an inert atmosphere of nitrogen.

Signed at Berkeleyin the county of Alanieda and Stateof Californiathis 1st day of Aug., 1922. v

'CLAUDE G. M'INER. 

